Evo 6 extreme dump valve suddenly got louder, help required!

[Scooby P1]

Hi all

My brother has an Evo 6 extreme RS450, a rare machine with forged engine etc etc.
however, due to lack of use and snow / cold etc the battery went flat and as its not been mapped since he spent 6 months rebuilding it (it's running VERY, very rich), after we could not get it started it turned out that the spark plugs were screwed as well.
New plugs, full battery and it works again.

HOWEVER, the dump valve / waste gate suddenly sounds completely different - a very loud whoosh, like an after market blow-off, which in the 500 miles or so since he rebuilt it, it has never sounded like before. This is accompanied by the occasional loud pop / bang from the exhaust when changing gear in 1st / 2nd after decent boost / foot down.

Is this a result of it not being used much for 3-4 weeks, and the few miles it has done has never been out of 3rd gear?
But the most pressing question is why has the dump valve sound changed to a really noisy one, whilst seemingly not affecting the car's performance at all?

appreciate any help.

[ScoobieWRX]

If it's the original air bypass valve is it meant to be plumbed in recirculating configuration i.e. back to the turbo inlet pipe, or is it meant to be vent to atmosphere (VTA) as standard.

I'm not up on these but if it's suddenly very loud it may be the recirculating hose has blown off, if it has one, or hasn't been connected.

[liner33]

Probably just free'ing up a little with use , if I understand it the car was left unused for a long time , probably got a bit sticky

[Scooby P1]

ScoobieWRX said:

If it's the original air bypass valve is it meant to be plumbed in recirculating configuration i.e. back to the turbo inlet pipe, or is it meant to be vent to atmosphere (VTA) as standard.

I'm not up on these but if it's suddenly very loud it may be the recirculating hose has blown off, if it has one, or hasn't been connected.

Thanks for your help mate, been a while since i've asked on a Jap forum but it's always you who helps me!!
i shall ask him to find that out and see what the response is.

Quick question from me....my power steering pump is on its way out - does that mean that on full lock when parking it can make a noise from around new one that doesn't cost £500 from subaru??

[UTH]

I'm fairly sure it's a recirculating valve.....

[ScoobieWRX]

Scooby P1 said:

ScoobieWRX said:

If it's the original air bypass valve is it meant to be plumbed in recirculating configuration i.e. back to the turbo inlet pipe, or is it meant to be vent to atmosphere (VTA) as standard.

I'm not up on these but if it's suddenly very loud it may be the recirculating hose has blown off, if it has one, or hasn't been connected.

Thanks for your help mate, been a while since i've asked on a Jap forum but it's always you who helps me!!
i shall ask him to find that out and see what the response is.

Quick question from me....my power steering pump is on its way out - does that mean that on full lock when parking it can make a noise from around new one that doesn't cost £500 from subaru??

When the steering is properly on full lock they usually make a little noise. If it's making a very loud noise on full lock the either your power steering fluid is low or it is definitely on it's way out. I found when i did mine the steering was getting progressively heavier as time when by until it finally died.

Have a chat to Andy at Grade A Subaru. He'll be able to sort out a used pump for you. I'd also replace the old belt with a brand spanking new one which you can source either from Grade A or your local Subaru stealership.

When you replace the pump fill the system completely and turn the wheel if you can from side to side just to gravity feed the steering column recirculating steering valve. Make sure the resevoir is full to the mark. You can always suck some out if it's overfilled later on. Then switch the engine on and very slowly start turning the steering wheel from side to side, do this several times. If it still feels not quite right or is making any noise then you need to bleed the system. There are two bleed valves on the rack where the steering column goes into the rack. They are a pain to get to but you should be able to get rid of any last dregs of air with that.

[Mastodon2]

If the car is making a whooshing noise on the closing throttle then there has been a dump valve added at some point - the standard is a recirculating valve which is silent in operation. Are you sure it doesn't just seem louder as the car has been off the road? Sometimes the dump valve in my old Cupra R sounded like that satisfied "ahh" noise you make after taking a sip of beer on a hot day when driven gently, it hissed like an angry snake when you booted it and let off the throttle from a wide opening on high boost. I'd wager there is nothing wrong with it, it's all psychological.

Personally, they seem a "more trouble than they are worth" item at times, when I was using seatcupra.net, every other thread in the faults forum was about a dump valve causing the engine management system some bother.

[liner33]

Stock Evo 6 DV is far from silent !!

[UTH]

Mastodon2 said:

If the car is making a whooshing noise on the closing throttle then there has been a dump valve added at some point - the standard is a recirculating valve which is silent in operation. Are you sure it doesn't just seem louder as the car has been off the road? Sometimes the dump valve in my old Cupra R sounded like that satisfied "ahh" noise you make after taking a sip of beer on a hot day when driven gently, it hissed like an angry snake when you booted it and let off the throttle from a wide opening on high boost. I'd wager there is nothing wrong with it, it's all psychological.

Personally, they seem a "more trouble than they are worth" item at times, when I was using seatcupra.net, every other thread in the faults forum was about a dump valve causing the engine management system some bother.

The thing that's weird is that if I got in the car for the first time right now, I'd think that all these noises etc were normal and nothing was wrong, as it seems to drive fine. BUT the sound has definitely changed, I noticed it straight away, and that's the only reason I'm concerned is that things don't usually just change for no apparent reason...
I've got a 200 mile journey to do tomorrow, so will get a chance to really give it some gas, and i guess if all is ok, then I should stop worrying. Got a remap due next Friday as well, so hoping the car will be nearly perfect after that.

[UTH]

liner33 said:

Stock Evo 6 DV is far from silent !!

Really? I had a standard TME before this extreme and it made no noise coming off boost.

[liner33]

Of course it makes more noise if you have an aftermarket filter and increased boost

[ScoobieWRX]

The little bit of psshhhttt you're hearing from a recirculating air bypass valve is coming out via the air intake/induction end. The more boost the louder the noise, as has been said.